How to Interact with Web Forms. Part 2

Preselecting Multiple Selection Lists

When it comes to prefilling form elements, multiple selection lists are the most difficult ones to implement. This is because in $_GET or $_POST, you have an array of chosen options; so you cannot just compare strings, but you have to search for the specified value in the array. Luckily, PHP offers something suitable in the form of the in_array() function. So, the effort required is not much more than with the other form elements: If the current value is in $_GET/$_POST, print out the selected attribute.

However, the HTML form must be specially preparedto allow PHP to access the data from the multiple selection list:The value of the name attribute has to end with [], hinting to PHP that it should expect an array of values, not just a string value. Accessing the list data, however, can still be done using $_GET[‘listname‘]/$_POST[‘listname‘] and not $_GET[‘listname[]‘]/$_POST[‘listname[]‘], as shown in the preceding code.

If you want to prefill the list with data from the cookie, you just have to use the well-known file getFormData.inc.php from the previous phrases.

It contains two additional functions that return an array instead of a string.

These functions return an array for multiple lists that you can use as you did in select-multiple.php.

Processing Graphical Submit Buttons

Graphical Submit buttons (<input type=”image” />) are not only a nice way to spicen up the layout of the form, but they also offer a nice feature:The browser submits the x and the y coordinates of the mouse pointer when clicking on the button. In PHP, this happens by appending _x and _y to the name attribute of the button and writing this into $_GET or $_POST.The preceding code evaluates this information.

Created: March 27, 2003
Revised: January 23, 2006

URL: https://webreference.com/programming/php_forms2/1

How to Interact with Web Forms. Part 2